活性元素对C/NiAl复合材料界面润湿及浸渗组织的影响

Effect of active element on interface wettability and microstructure of NiAl-modified C/C composites prepared by infiltration

摘要:

采用座滴法研究了真空、1800℃下NiAl在碳、TiC、SiC和ZrC上的润湿性，并通过铺展实验和熔渗实验优化了NiAl改性C/C复合材料的活性添加元素及添加量。采用真空熔渗法制备NiAl改性C/C复合材料，采用X射线衍射和扫描电镜分析了复合材料的微观结构和渗透机制。结果表明，NiAl与碳或SiC的润湿性较差，与TiC或ZrC的润湿性很好；添加Ti能改善NiAl和碳的润湿性，Ti粉含量(质量分数)为15%时，C/C 复合材料熔渗NiAl的效果最佳，NiAl渗透层的厚度约为0.8~0.9 mm；添加Ti利于C/C复合材料渗NiAl的主要原因是Ti与C反应形成TiC，改善了NiAl在C/C复合材料中的化学吸附和物理吸附特性，NiAl通过毛细管力作用渗入到C/C复合材料坯体中。

Abstract:

Wetting behaviors of carbon, TiC, SiC or ZrC by molten NiAl intermetallic compound at 1800℃ were investigated by the sessile drop technique under vacuum. Active element and addition quantity were optimized by spreading and infiltrating experiment in the NiAl-modified C/C composite. NiAl-modified C/C composites were prepared by the vacuum molten infiltration. The microstructures and infiltration mechanism were analysed by X-ray diffraction (XRD) and scanning electronic microscopy (SEM). The results show that NiAl has lower wettability on carbon or SiC, while has higher wettability on TiC or ZrC. It is indicated that adding Ti can improve the wettability between C/C composites and NiAl intermetallic. NiAl with about 15%Ti (mass fraction) possesses good wettability on the surface of C/C composites. The death of NiAl permeable layer on C/C composite is about 0.8~0.9 mm. The molten NiAl intermetallic compound containing titanium infiltrates into the C/C composites preform, and TiC phase forms in the NiAl-modified C/C composites. The improvement of adding titanium for molten NiAl infiltration into the C/C composites preform results from the improvement of the chemical and physical adsorption characteristic of NiAl on the composites. The liquid NiAl infiltrates into the preform under the capillary pressure.